It is thought he had been enjoying a week-long taste of freedom on temporary release from an open prison in Gloucestershire.

He has served 31 years behind bars as the Parole Board had previously refused to release him, although he is now being allowed short periods out of jail ahead of returning to society.

However, Helen's family told the Daily Mail they were "appalled" to see pictures of him out and about.

Helen's mother Marie has for years campaigned to bring in what has been dubbed Helen's Law, which would mean murderers could never be eligible for parole if they do not say where their victim's remains are.

Mrs McCourt, 75, told the national newspaper: "Why should he be allowed his freedom when I still haven’t been able to bury my daughter after all these years?

"He should not be afforded any days out – he’s a dangerous, evil killer. It is heaping more misery on our suffering.

"I’m absolutely appalled. I was only in Birmingham on Monday, I could have walked past him in the street without knowing.

"This evil man is walking around, enjoying the sunshine while my daughter is hidden somewhere, discarded, as the judge said at the trial, with the rats."

When confronted by the Mail, former pub landlord Simms denied he knew where Helen's body was, saying if he did he would not have spent more than a decade and a half beyond his original tariff behind bars.